Composite syringe

Abstract: A composite syringe has an injector body (1) and a cylindrical protector (2) which covers a cylinder (14) of the injector body (1). The protector (2) includes a sleeve (22) separably connected to a base (21) which is secured to an outer periphery of the cylinder's forward end. The sleeve (22), when separated from the base (21), is caused to slide towards the cylinder's end and beyond a tip (15) holding a needle (3), until it engages again with the base (21) at a position where the needle (3) is covered entirely with the sleeve (22). This prevents any accident of erroneous pricking or puncture of a user of the syringe or other people coming into contact with the syringe.

Description: The invention relates to a composite syringe comprising: an injector body; and a cylindrical protector covering the injector body; said injector body comprising: a cylinder; a tip extending from the cylinder for holding a medical needle; and a skirt surrounding the tip and extending coaxially thereof; said cylindrical protector comprising: a sleeve slidable on the cylinder toward said tip; a base surrounding and firmly held to the skirt, said sleeve extending from said base towards the rear of said injector body, the syringe further including: a lockable member formed on an inner periphery of said sleeve; and a locking member formed on the outer periphery of said base. In particular, the invention provides a disposable composite syringe, and, more particularly, provides a composite syringe in which the needle can be sealed so as to prevent erroneously pricking or puncturing people who may come into contact with the syringe. Every medical needle, once used, is usually thrown away, whether it is an ordinary needle of the injector type or a vein needle retained for intravenous drip injection of a liquid medicine or for transfusion of blood. The acute needle ends are covered with proper protectors, before being discarded, in order to prevent injury to the people who come into contact with the needles. However, those who work in various medical fields and handle the needles are still exposed to danger, because the needle ends may possibly cause injury when attaching the protectors thereto. Such an accident could cause a serious problem in addition to the simple pain due to a skin prick. For example, the needle ends which have been used on patients are sometimes polluted or exposed to various pathogens such as bacilli and viruses, thereby exposing healthy people to such bacilli and viruses. Many ideas directed to prevention of such an erroneous exposure by the used needles include those which are disclosed in the Japanese Unexamined Utility Model Publications: Sho. 60-55448; Sho. 61-85239; Hei. 4-58256, the Unexamined Patent Publications: Hei. 4-244167; Hei. 2-1288; Hei. 4-90766; Sho. 62-144666; Sho. 63-317160; Sho. 64-86981, and the Domestic Re-Publication of Unexamined International Patent Application: Hei. 3-504808. Publications 60-55448 and 61-85239 disclose protectors that have sockets of a modified shape. An example of the sockets has an enlarged diameter enlarged towards its end with another socket having a flange adjacent thereto, and still another socket has slits extending longitudinally thereof. Disclosed in Publications 4-58256 and 4-244167 are some specially designed protectors. One of them has a bellows that can be stretched towards an end thereof to fully cover the injector. The other protector comprises a housing that consists of a basal portion and a compressible portion flexibly connected thereto. An acute end of the injector needle accommodated in this housing is caused to pierce the retracted compressible portion. Disclosed in Re-Publication 3-504808, Publications 2-1288 and 4-90766 are injectors each comprising a retractable needle. Plungers engage with and retract the used needles into outer cylinders. Further, Publications 62-144666, 63-317160 and 64-86981 disclose injectors each having a cylindrical protector fitted on an outer cylinder. This protector is slidable longitudinally of the cylinder so as to cover the whole injector. The various prior art injectors listed and discussed above seem to be effective in preventing the needles from unintentionally pricking the user's skin. However, they still are disadvantageous for the following reasons. The modified socket protectors must be removed from and fitted again on the used injectors. Such a re-fitting of the socket will possibly cause an accidental, erroneous pricking of the skin. Sockets of a complicated structure will increase manufacturing cost and complicate use of the injectors. Injectors having retractable needles cannot be manufactured merely by modifying the conventional design of ordinary injectors. A sophisticated structure for injectors of this type will not only render them expensive but also difficult to use. Injectors of the other type having the slidable protectors are easier to operate, although certain means or members for slidably holding the protectors must be added to the ordinary injectors. Such additional means or members will also increase manufacture cost. Furthermore, a composite syringe of the type mentioned in the beginning is disclosed in US-A-4 631 057. In this syringe the base and the sleeve, prior to use of the syringe, are releasably connected to one another by a rib on the interior surface of the sleeve, which is seated in an annular groove on the exterior surface of the base. After use of the syringe, the groove serves as a safety or backup to catch teeth provided as lockable members on the inner periphery of the sleeve so that movement of the sleeve completely off the syringe body is prevented. However, this construction of the composite syringe according to US-A-4 631 057 has serious drawbacks which clearly expose that person who uses the syringe to the danger of being pricked by the injection needle and to thereby being infected with various pathogens such as bacilli and viruses contained in the blood of a patient: (A) At first, in the using position of the syringe, since the base and the forward end of the sleeve are fastened to one another by the annular groove and the annular rib and are supported relative to one another by contact of the inner surface of the sleeve and the outer surface of the base, the clearance between those surfaces must be relatively small. This causes resistance against release of the connection and against relative movement between the base and the sleeve. Therefore, when the user grips the sleeve and tries to force it forward to disconnect the base and the sleeve from one another, there is the risk that his hand may slip forwardly off from the sleeve and get pricked by the tip of the used needle and thereby become infected. (B) Secondly, even if the user has disconnected the base and the sleeve from one another, there is, due to the above resistance against relative movement between the base and the sleeve, during that relative movement the risk that the user's hand slips forwardly off from the sleeve and gets pricked by the used needle, particularly in the event of some clamping when the user applies a strong force to the sleeve, and thus the user can also become infected. Finally, WO-A-93 02728 discloses safety syringes, each made up of an enclosure unit and a cartridge-needle unit, with each cartridge-needle unit comprising a glass barrel having a piston and a needle assembly, wherein the needle is covered by a removable sheath of the enclosure unit. The enclosure unit further comprises a hollow body section and a stem section which is also hollow. The body section and the stem section are a one-piece molding connected at a frangible connection adjacent to a flange. The frangible connection is provided for releasing off a cap, i.e. the stem section, wrapped around the needle from the body section. However, the frangible connection is neither provided such that one of the connected members can be slid over the other member nor such that one of those members could be locked again to the other member by engagement therewith. SUMMARY OF THE INVENTION As a solution to the foregoing problems, it is an object of the present invention to provide an improved composite syringe that is simpler in structure, easier to operate and less expensive. This object is solved in accordance with the invention by a composite syringe of the type mentioned in the beginning which is characterized in that (1) said sleeve has an end portion connected to and breakable from an end portion of said base so that said sleeve is separable from said base and (2) said breakable connection between said sleeve and said base being designed such that after breaking said sleeve from said base said lockable member is engageable with said locking member so that said sleeve is locked in a position to circumferentially enclose the medical needle. Thus, a composite syringe provided herein comprises an injector body in combination with a cylindrical protector. The injector body comprises a cylinder, a tip extending therefrom to hold a medical needle, and a skirt extending coaxially with the tip so as to surround the tip. The protector is composed of a sleeve and a base, extending forward therefrom, to grasp or encircle the tip. The sleeve has its forward end breakable from a rear end of the base so that the sleeve can be broken off or detached from the base and slide forward on and along the cylinder. The composite syringe further has a lockable member formed on an inner periphery of the sleeve, and a locking member formed on an outer periphery of the base. The locking member is engageable with the lockable member so that the sleeve can be kept at a position to cover the whole needle. In one embodiment, the base is connected to the sleeve by at least one bridge element, i.e. by one or more thin bridges. Alternatively, the base may be integral with the sleeve provided that they are made of materials that are substantially immiscible with each other. The lockable member may preferable be lugs disposed on a rear end portion of the sleeve and engageable with an annular groove formed as the locking member on the base. Contrarily, the lockable member may be an annular groove engageable with lugs formed as the locking member. After use of the composite syringe, the protector's sleeve will be gripped by one hand, with a flange of the cylinder being twisted relative to the sleeve by the other hand. Then, the sleeve thus separated from the base and rendered longitudinally displaceable of the syringe will be moved forwards, so that the locking member moves into engagement with the lockable member at its position where the sleeve covers the whole needle for safe disposal of the used syringe. BRIEF DESCRIPTION OF THE DRAWINGS Now, embodiments of the present invention will be described referring to the drawings, in which: Fig. 1 is a plan view of a composite syringe comprising a protector in an embodiment, with a longitudinal half of the protector being shown in cross section; Fig. 2 is a cross-sectional view of the protector, taken along an axis thereof; Fig. 3 is a cross section taken along the line A - A in Fig. 2; Fig. 4 shows an encircled portion B in Fig. 2, on an enlarged scale; Fig. 5 shows an encircled portion C in Fig. 3, on an enlarged scale; Fig. 6 is a plan view of the composite syringe shown in Fig. 1 with a needle attached thereto and having the protector; and Fig. 7 is a plan view of the protector shown in Fig. 6 and comprising a sleeve and a base, with the sleeve (shown in cross section) shifted forwards to engage with the base. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 illustrates a composite syringe provided in an embodiment of the present invention. The syringe comprises an injector body 1 and a cylindrical protector 2 fitted on a cylinder 14 of the injector body. The protector 2 comprises a base 21 and a sleeve 22, with the base 21 secured to an outer periphery of a forward end of the cylinder 14. The sleeve 22 connected to the base 21 is separable therefrom and, if so separated, can slide towards a forward end of the cylinder 14 to a position where a needle 3 held by a tip 15 is wholly covered. The sleeve will immovably engage again with the base 21 at that forward end position. The injector body 1 comprises a skirt 16, in addition to a tip 15 for holding a needle as in the case with ordinary injectors. The skirt 16 employed in the present invention surrounds and extends coaxially of the tip 15. Typically, the ordinary injectors are of the so-called "lockable" type in which the needles are screwed to or "Luer-connected" to the tips. Thus, the injector body 1 can be of any conventional type, and no detailed description thereof will be given here. As Fig. 1 shows, a plunger 11 inserted in the cylinder 14 of this body 1 comprises a rod 13 and a gasket 12 secured to a forward end of the rod. A flange 17 formed integral with a rear end of the cylinder 14 will bear against the first and second fingers of a user when he or she presses the plunger 11 in a forward direction with his or her thumb. The tip 15 is formed at the forward end of the cylinder 14, as noted above, and is surrounded by the skirt 16 which extends coaxially of the tip. The needle 3 may be screwed to an inner peripheral thread (not shown) of the skirt, or alternatively be locked therein by the "Luer" connection. The protector 2, comprising the base 21 and the sleeve 22, is of a cylindrical shape to cover the cylinder 14 of the injector body 1. The base 21 has an inner periphery 26 firmly held in place on an outer periphery of the forward end, i.e., skirt 16. The sleeve 22 extends rearward from a rearward end of the base 21 and terminates a little short of the flange 17 of the cylinder 14. The rearward end of the base 21, connected to a forward end of the sleeve 22, is readily separable from the sleeve 22, for example, by twisting the sleeve relative to the base. The sleeve 22, if separated from the base, can slide forwards on and along the cylinder 14 of the injector body 1. Thus, the sleeve 22 can be moved to a position so as to wholly cover the needle held by the tip 15. An annular groove 25 is formed as the locking member around a forward portion of the base 21. The base 21 is tapered to increase its diameter from its rearward end in a direction towards the groove. Lugs 24 protrude from an inner periphery of the rear end of the sleeve 22 and serve as a lockable member. These lugs 24 will engage with the annular groove 25 when the sleeve is moved to its foremost position so as to cover the needle in its entirety (see Fig 7). In the example of Fig. 1, thin bridges 23 connect the sleeve 22 to the base 21 of the protector in the manner shown in Figs. 2 to 5. In other examples not shown, an intentional weld line, (i.e., an imperfectly welded zone) is formed along the boundary between the base and the sleeve, or two materials of different colors and immiscible with one another may form the base and sleeve, respectively. The number of thin bridges is preferably two or more, though a single bridge will suffice. The lockable and locking members for keeping the sleeve at the aforesaid foremost position covering the needle need not necessarily be the lugs and groove, respectively, formed on or in the sleeve and the base. Instead, the sleeve may be formed with an inner, annular groove in which lugs, provided on the base, are received in the groove. The lockable and locking members may be of other shapes, and a single or annular lug may be used to lock the sleeve to the base. Figs. 6 and 7 illustrate operation of the composite syringe of the present invention. As shown in Fig. 6, the needle 3, before use, is mounted on the tip 15 of the cylinder 14. The syringe 1 is used in medical operations such as the injection of a liquid medicine or the collection or transfusion of blood. After use in the medical operation, the composite syringe will be discarded in the following manner. An operator grips the sleeve 22 with one of his or her hands, and grips the flange 17 of the injector body 1 with the other hand. The operator will then twist the flange or sleeve clockwise or anticlockwise, relative to one another and around their longitudinal axis. As a result, the thin bridges 23 will be broken so as to separate the sleeve 22 from the base 21. Subsequently, the sleeve 22 can be moved along the cylinder 14 toward the forward end, i.e., the needle end, until the sleeve's lugs 24 snap in the groove 25 of the base at a position where the sleeve 22 wholly covers the needle 3. The sleeve in this position cannot move forwards or backwards, since its lugs bear against the forward wall of the groove 25 to prevent forward movement and the rear tapered portion of the base 21 provides a sufficiently high rearward wall of the groove to prevent rearward movement. The composite syringe will be thrown away after the protecting sleeve 22 has been moved to a stable position covering the needle 3. As will now be apparent, the composite syringe provided herein is simpler in structure, easier to operate and much less expensive than the syringes of the prior art types. Further, medical personnel and doctors are positively protected from being accidently and erroneously pricked by the used needles when discarding the used syringes.

Claims: A composite syringe comprising: an injector body (1); and a cylindrical protector (2) covering the injector body (1); said injector body (1) comprising: a cylinder (14); a tip (15) extending from the cylinder (14) for holding a medical needle (3); and a skirt (16) surrounding the tip (15) and extending coaxially thereof; said cylindrical protector (2) comprising: a sleeve (22) slidable on the cylinder (14) toward said tip (15); a base (21) surrounding and firmly held to the skirt (16), said sleeve (22) extending from said base (21) towards the rear of said injector body (1), the syringe further including: a lockable member (24) formed on an inner periphery of said sleeve (22); and a locking member (25) formed on the outer periphery of said base (21), characterized in that (1) said sleeve (22) has an end portion connected to and breakable from an end portion of said base (21) so that said sleeve (22) is separable from said base (21) and (2) said breakable connection between said sleeve (22) and said base (21) being designed such that after breaking said sleeve (22) from said base (21) said lockable member (24) is engageable with said locking member (25) so that said sleeve (22) is locked in a position to circumferentially enclose the medical needle (3). A composite syringe as defined in claim 1, characterized in that said base (21) is connected to said sleeve (22) by at least one bridge element (23). A composite syringe as defined in claim 1 or 2, characterized in that said base (21) and said sleeve (22) are integral with one another and formed of materials substantially immiscible with each other. A composite syringe as defined in any one of claims 1 to 3, characterized in that the lockable member (24) is a plurality of lugs positioned on an inner periphery of the rear end portion of said sleeve (22), and the locking member (25) is an annular groove formed on an outer periphery of said base (21). A composite syringe as defined in any one of claims 1 to 3, characterized in that the lockable member (24) is an annular groove provided on an inner periphery of the rear end portion of said sleeve (22), and the locking member (25) is a plurality of lugs positioned on an outer periphery of said base (21). A composite syringe as defined in any one of claims 1 to 5, characterized in that said sleeve (22) is extendible concentrically with the medical neede (3) to a length which is greater than a predetermined length of the medical needle (3).

Inventors: KISHIGAMI YOSHIKAZU, KISHIGAMI, YOSHIKAZU
Applicants: NISSHO KK, NISSHO CORPORATION
Application year: 1994
Main classification: A61M5
IPC codes: A61M5